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nbd: Share common option-sending code in client

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Rather than open-coding each option request, it's easier to
have common helper functions do the work.  That in turn requires
having convenient packed types for handling option requests
and replies.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-9-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Eric Blake 2016-10-14 13:33:10 -05:00 committed by Paolo Bonzini
parent 3668328303
commit c8a3a1b6c4
3 changed files with 131 additions and 151 deletions
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25
include/block/nbd.h
View File

@ -26,15 +26,34 @@
#include "io/channel-socket.h"
#include "crypto/tlscreds.h"
/* Note: these are _NOT_ the same as the network representation of an NBD
/* Handshake phase structs - this struct is passed on the wire */
struct nbd_option {
uint64_t magic; /* NBD_OPTS_MAGIC */
uint32_t option; /* NBD_OPT_* */
uint32_t length;
} QEMU_PACKED;
typedef struct nbd_option nbd_option;
struct nbd_opt_reply {
uint64_t magic; /* NBD_REP_MAGIC */
uint32_t option; /* NBD_OPT_* */
uint32_t type; /* NBD_REP_* */
uint32_t length;
} QEMU_PACKED;
typedef struct nbd_opt_reply nbd_opt_reply;
/* Transmission phase structs
*
* Note: these are _NOT_ the same as the network representation of an NBD
* request and reply!
*/
struct NBDRequest {
uint64_t handle;
uint64_t from;
uint32_t len;
uint16_t flags;
uint16_t type;
uint16_t flags; /* NBD_CMD_FLAG_* */
uint16_t type; /* NBD_CMD_* */
};
typedef struct NBDRequest NBDRequest;

255
nbd/client.c
View File

@ -75,64 +75,128 @@ static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
*/
/* Send an option request.
*
* The request is for option @opt, with @data containing @len bytes of
* additional payload for the request (@len may be -1 to treat @data as
* a C string; and @data may be NULL if @len is 0).
* Return 0 if successful, -1 with errp set if it is impossible to
* continue. */
static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt,
uint32_t len, const char *data,
Error **errp)
{
nbd_option req;
QEMU_BUILD_BUG_ON(sizeof(req) != 16);
/* If type represents success, return 1 without further action.
* If type represents an error reply, consume the rest of the packet on ioc.
* Then return 0 for unsupported (so the client can fall back to
* other approaches), or -1 with errp set for other errors.
if (len == -1) {
req.length = len = strlen(data);
}
TRACE("Sending option request %" PRIu32", len %" PRIu32, opt, len);
stq_be_p(&req.magic, NBD_OPTS_MAGIC);
stl_be_p(&req.option, opt);
stl_be_p(&req.length, len);
if (write_sync(ioc, &req, sizeof(req)) != sizeof(req)) {
error_setg(errp, "Failed to send option request header");
return -1;
}
if (len && write_sync(ioc, (char *) data, len) != len) {
error_setg(errp, "Failed to send option request data");
return -1;
}
return 0;
}
/* Receive the header of an option reply, which should match the given
* opt. Read through the length field, but NOT the length bytes of
* payload. Return 0 if successful, -1 with errp set if it is
* impossible to continue. */
static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
nbd_opt_reply *reply, Error **errp)
{
QEMU_BUILD_BUG_ON(sizeof(*reply) != 20);
if (read_sync(ioc, reply, sizeof(*reply)) != sizeof(*reply)) {
error_setg(errp, "failed to read option reply");
return -1;
}
be64_to_cpus(&reply->magic);
be32_to_cpus(&reply->option);
be32_to_cpus(&reply->type);
be32_to_cpus(&reply->length);
TRACE("Received option reply %" PRIx32", type %" PRIx32", len %" PRIu32,
reply->option, reply->type, reply->length);
if (reply->magic != NBD_REP_MAGIC) {
error_setg(errp, "Unexpected option reply magic");
return -1;
}
if (reply->option != opt) {
error_setg(errp, "Unexpected option type %x expected %x",
reply->option, opt);
return -1;
}
return 0;
}
/* If reply represents success, return 1 without further action.
* If reply represents an error, consume the optional payload of
* the packet on ioc. Then return 0 for unsupported (so the client
* can fall back to other approaches), or -1 with errp set for other
* errors.
*/
static int nbd_handle_reply_err(QIOChannel *ioc, uint32_t opt, uint32_t type,
static int nbd_handle_reply_err(QIOChannel *ioc, nbd_opt_reply *reply,
Error **errp)
{
uint32_t len;
char *msg = NULL;
int result = -1;
if (!(type & (1 << 31))) {
if (!(reply->type & (1 << 31))) {
return 1;
}
if (read_sync(ioc, &len, sizeof(len)) != sizeof(len)) {
error_setg(errp, "failed to read option length");
return -1;
}
len = be32_to_cpu(len);
if (len) {
if (len > NBD_MAX_BUFFER_SIZE) {
if (reply->length) {
if (reply->length > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "server's error message is too long");
goto cleanup;
}
msg = g_malloc(len + 1);
if (read_sync(ioc, msg, len) != len) {
msg = g_malloc(reply->length + 1);
if (read_sync(ioc, msg, reply->length) != reply->length) {
error_setg(errp, "failed to read option error message");
goto cleanup;
}
msg[len] = '\0';
msg[reply->length] = '\0';
}
switch (type) {
switch (reply->type) {
case NBD_REP_ERR_UNSUP:
TRACE("server doesn't understand request %" PRIx32
", attempting fallback", opt);
", attempting fallback", reply->option);
result = 0;
goto cleanup;
case NBD_REP_ERR_POLICY:
error_setg(errp, "Denied by server for option %" PRIx32, opt);
error_setg(errp, "Denied by server for option %" PRIx32,
reply->option);
break;
case NBD_REP_ERR_INVALID:
error_setg(errp, "Invalid data length for option %" PRIx32, opt);
error_setg(errp, "Invalid data length for option %" PRIx32,
reply->option);
break;
case NBD_REP_ERR_TLS_REQD:
error_setg(errp, "TLS negotiation required before option %" PRIx32,
opt);
reply->option);
break;
default:
error_setg(errp, "Unknown error code when asking for option %" PRIx32,
opt);
reply->option);
break;
}
@ -147,58 +211,29 @@ static int nbd_handle_reply_err(QIOChannel *ioc, uint32_t opt, uint32_t type,
static int nbd_receive_list(QIOChannel *ioc, char **name, Error **errp)
{
uint64_t magic;
uint32_t opt;
uint32_t type;
nbd_opt_reply reply;
uint32_t len;
uint32_t namelen;
int error;
*name = NULL;
if (read_sync(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
error_setg(errp, "failed to read list option magic");
if (nbd_receive_option_reply(ioc, NBD_OPT_LIST, &reply, errp) < 0) {
return -1;
}
magic = be64_to_cpu(magic);
if (magic != NBD_REP_MAGIC) {
error_setg(errp, "Unexpected option list magic");
return -1;
}
if (read_sync(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
error_setg(errp, "failed to read list option");
return -1;
}
opt = be32_to_cpu(opt);
if (opt != NBD_OPT_LIST) {
error_setg(errp, "Unexpected option type %" PRIx32 " expected %x",
opt, NBD_OPT_LIST);
return -1;
}
if (read_sync(ioc, &type, sizeof(type)) != sizeof(type)) {
error_setg(errp, "failed to read list option type");
return -1;
}
type = be32_to_cpu(type);
error = nbd_handle_reply_err(ioc, opt, type, errp);
error = nbd_handle_reply_err(ioc, &reply, errp);
if (error <= 0) {
return error;
}
len = reply.length;
if (read_sync(ioc, &len, sizeof(len)) != sizeof(len)) {
error_setg(errp, "failed to read option length");
return -1;
}
len = be32_to_cpu(len);
if (type == NBD_REP_ACK) {
if (reply.type == NBD_REP_ACK) {
if (len != 0) {
error_setg(errp, "length too long for option end");
return -1;
}
} else if (type == NBD_REP_SERVER) {
} else if (reply.type == NBD_REP_SERVER) {
if (len < sizeof(namelen) || len > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "incorrect option length");
error_setg(errp, "incorrect option length %" PRIu32, len);
return -1;
}
if (read_sync(ioc, &namelen, sizeof(namelen)) != sizeof(namelen)) {
@ -240,7 +275,7 @@ static int nbd_receive_list(QIOChannel *ioc, char **name, Error **errp)
}
} else {
error_setg(errp, "Unexpected reply type %" PRIx32 " expected %x",
type, NBD_REP_SERVER);
reply.type, NBD_REP_SERVER);
return -1;
}
return 1;
@ -251,24 +286,10 @@ static int nbd_receive_query_exports(QIOChannel *ioc,
const char *wantname,
Error **errp)
{
uint64_t magic = cpu_to_be64(NBD_OPTS_MAGIC);
uint32_t opt = cpu_to_be32(NBD_OPT_LIST);
uint32_t length = 0;
bool foundExport = false;
TRACE("Querying export list");
if (write_sync(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
error_setg(errp, "Failed to send list option magic");
return -1;
}
if (write_sync(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
error_setg(errp, "Failed to send list option number");
return -1;
}
if (write_sync(ioc, &length, sizeof(length)) != sizeof(length)) {
error_setg(errp, "Failed to send list option length");
if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) {
return -1;
}
@ -314,72 +335,29 @@ static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
QCryptoTLSCreds *tlscreds,
const char *hostname, Error **errp)
{
uint64_t magic = cpu_to_be64(NBD_OPTS_MAGIC);
uint32_t opt = cpu_to_be32(NBD_OPT_STARTTLS);
uint32_t length = 0;
uint32_t type;
nbd_opt_reply reply;
QIOChannelTLS *tioc;
struct NBDTLSHandshakeData data = { 0 };
TRACE("Requesting TLS from server");
if (write_sync(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
error_setg(errp, "Failed to send option magic");
return NULL;
}
if (write_sync(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
error_setg(errp, "Failed to send option number");
return NULL;
}
if (write_sync(ioc, &length, sizeof(length)) != sizeof(length)) {
error_setg(errp, "Failed to send option length");
return NULL;
}
TRACE("Getting TLS reply from server1");
if (read_sync(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
error_setg(errp, "failed to read option magic");
return NULL;
}
magic = be64_to_cpu(magic);
if (magic != NBD_REP_MAGIC) {
error_setg(errp, "Unexpected option magic");
return NULL;
}
TRACE("Getting TLS reply from server2");
if (read_sync(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
error_setg(errp, "failed to read option");
return NULL;
}
opt = be32_to_cpu(opt);
if (opt != NBD_OPT_STARTTLS) {
error_setg(errp, "Unexpected option type %" PRIx32 " expected %x",
opt, NBD_OPT_STARTTLS);
if (nbd_send_option_request(ioc, NBD_OPT_STARTTLS, 0, NULL, errp) < 0) {
return NULL;
}
TRACE("Getting TLS reply from server");
if (read_sync(ioc, &type, sizeof(type)) != sizeof(type)) {
error_setg(errp, "failed to read option type");
if (nbd_receive_option_reply(ioc, NBD_OPT_STARTTLS, &reply, errp) < 0) {
return NULL;
}
type = be32_to_cpu(type);
if (type != NBD_REP_ACK) {
if (reply.type != NBD_REP_ACK) {
error_setg(errp, "Server rejected request to start TLS %" PRIx32,
type);
reply.type);
return NULL;
}
TRACE("Getting TLS reply from server");
if (read_sync(ioc, &length, sizeof(length)) != sizeof(length)) {
error_setg(errp, "failed to read option length");
return NULL;
}
length = be32_to_cpu(length);
if (length != 0) {
if (reply.length != 0) {
error_setg(errp, "Start TLS response was not zero %" PRIu32,
length);
reply.length);
return NULL;
}
@ -467,8 +445,6 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint16_t *flags,
if (magic == NBD_OPTS_MAGIC) {
uint32_t clientflags = 0;
uint32_t opt;
uint32_t namesize;
uint16_t globalflags;
bool fixedNewStyle = false;
@ -518,28 +494,13 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint16_t *flags,
goto fail;
}
}
/* write the export name */
magic = cpu_to_be64(magic);
if (write_sync(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
error_setg(errp, "Failed to send export name magic");
goto fail;
}
opt = cpu_to_be32(NBD_OPT_EXPORT_NAME);
if (write_sync(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
error_setg(errp, "Failed to send export name option number");
goto fail;
}
namesize = cpu_to_be32(strlen(name));
if (write_sync(ioc, &namesize, sizeof(namesize)) !=
sizeof(namesize)) {
error_setg(errp, "Failed to send export name length");
goto fail;
}
if (write_sync(ioc, (char *)name, strlen(name)) != strlen(name)) {
error_setg(errp, "Failed to send export name");
/* write the export name request */
if (nbd_send_option_request(ioc, NBD_OPT_EXPORT_NAME, -1, name,
errp) < 0) {
goto fail;
}
/* Read the response */
if (read_sync(ioc, &s, sizeof(s)) != sizeof(s)) {
error_setg(errp, "Failed to read export length");
goto fail;

2
nbd/nbd-internal.h
View File

@ -62,7 +62,7 @@
#define NBD_REPLY_MAGIC 0x67446698
#define NBD_OPTS_MAGIC 0x49484156454F5054LL
#define NBD_CLIENT_MAGIC 0x0000420281861253LL
#define NBD_REP_MAGIC 0x3e889045565a9LL
#define NBD_REP_MAGIC 0x0003e889045565a9LL
#define NBD_SET_SOCK _IO(0xab, 0)
#define NBD_SET_BLKSIZE _IO(0xab, 1)